This is Black Shiner, a product made by Drying. Depending on their properties, Processed Materials can be used in Alchemy, Cooking, or Crafting. Through Processing, you can improve a material's preservability and quality, or make it usable in some other way. Processing knowledge can be acquired by increasing Amity with certain people or completing a Quest. You can only dry things when it's sunny. You can improve the preservability of meat and fish by drying it, but this causes a decrease in quality.
Knowledge: